Pablo Martinez Monsivais, Associated Press
President Barack Obama, center, with Sec. of Defense Chuck Hagel, left, and Gen. Lloyd J. Austin III, right, Commander of the US Central Command (CentCom), before the start of a briefing at MacDill Air Force Base, Fla., Wednesday, Sept. 17, 2014. Obama was being updated on the ongoing military campaigns in Iraq and Syria.

WASHINGTON — Wary House lawmakers prepared to give President Barack Obama authority to arm and train Syrian rebels in the fight against Islamic State militants Wednesday as Iraq's new prime minister dismissed the notion that the struggle could lead to U.S. forces again fighting on the ground in his country.

"Not only is it not necessary, we don't want them. We won't allow them," Prime Minister Haider al-Abadi said in an interview with The Associated Press.

Congress appears inclined to give Obama the authority he wants — the first vote was likely in the House on Wednesday — but lawmakers are sharply divided over whether the U.S. should be doing more or less. Some Republicans contend that Islamic State militants occupying large portions of Iraq and Syria cannot be defeated without U.S. ground troops backing up airstrikes in Iraq. Many Democrats oppose resuming a war in Iraq that the U.S. exited three years ago.

The White House was quick to reject a suggestion by the nation's top military officer, Army Gen. Martin Dempsey, that he might recommend U.S. ground troops if Obama's current strategy doesn't work. Top House Democrat Nancy Pelosi said that regardless of Wednesday's vote, Democrats "are not supporting combat troops."

Obama's more-limited approach seemed headed for approval, though the vote may be closer than the president would like.

"If we want to open a front against (Islamic State forces) in Syria, we have to open a front. And I don't see any other way to do it than try to build an alternative force," said Rep. Adam Smith of Washington, top Democrat on the House Armed Services Committee. "No one's excited about it but, you know, it's the best from a series of bad options."

"Committing insufficient force in any conflict is self-defeating, and air strikes alone cannot win a war," Rep. Tom McClintock, R-Calif., warned Wednesday.

Republican leaders have swung behind Obama's request, though they're not pressuring the GOP rank and file to follow suit.

"I think there's a lot more that we need to be doing, but there's no reason for us not to do what the president asked us to do," Speaker John Boehner, R-Ohio, said. Pelosi, D-Calif., also supports the limited mission, as does Senate GOP leader Mitch McConnell of Kentucky. The measure would send U.S. military trainers to Saudi Arabia to arm and train Syrian opponents of Islamic State militants, who have routed U.S.-trained Iraqi security forces repeatedly and threaten the viability of the government in Baghdad.

Obama has also vowed to use air power to strike Islamic State militants but has maintained repeatedly that American forces will not have a renewed ground combat mission in Iraq in this new phase of a long battle against terrorists.

However, in a Senate hearing Tuesday, Dempsey said U.S. ground troops may be needed to battle the Islamic State group.

Dempsey told the Senate Armed Services Committee that if Obama's current approach isn't enough to prevail, he might "go back to the president and make a recommendation that may include the use of ground forces."

That drew a polite but prompt rebuttal from the White House. Obama "will not deploy ground troops in a combat role into Iraq or Syria," spokesman Josh Earnest said.

The White House position was endorsed on Wednesday by Iraqi Prime Minister al-Abadi, who rejected the idea of any foreign combat troops on Iraqi soil, despite the presence of U.S. military advisers there now.

At the same time, the Islamic State group released a video warning the United States that its fighters are waiting in Iraq if Obama sends troops there.

The short video shows images of militants blowing up tanks and wounded U.S. soldiers. It then shows a clip of Obama saying that combat troops will not be returning to Iraq, ending with a text overlay that reads "fighting has just begun."

The new congressional authority for Obama's plan would be added to a spending bill that's needed to keep the government running into December and avoid a politically damaging repeat of last year's partial shutdown of government agencies.

The underlying spending bill would also:

—Renew the charter of the Export-Import Bank, which helps finance foreign purchases of U.S. exports, through next June. That postpones a battle between tea party forces opposing the bank and more establishment Republicans who support it.

—Provide $88 million for the government's response to the Ebola outbreak in West Africa. A much larger, $560 million request is pending that would send troops and detection teams, and build infrastructure such as a headquarters and new labs in Africa.

The Senate could vote on the measure as early as Thursday, but the vote is likely to be close there as well as a number of Democrats have expressed skepticism.

"Interventions have failed in Lebanon, Somalia, Libya and Iraq, and Afghanistan is on the brink of failure," said Rep. Joe Manchin, D-W.Va. "What have we learned from our actions? Certainly not that going into Muslim countries to restore order or establish democracy is a winning strategy."

AP National Security Writer Robert Burns in Paris contributed to this report.